Submillimetre negative differential conductivity at the cyclotron frequency in As in strong fields

Abstract

In this paper it is shown theoretically that under certain conditions a cyclotron resonance maser based on -type materials can be fabricated. Strong crossed electric and magnetic fields , in which electrons in the central conduction band valley move dynamically (ballistically) up to the energy of the onset of intervalley scattering , are considered. The working temperatures of these masers could be increased to 80 K. The investigations have been carried out for the solid-solution composition with 0<x<0.39 (, where is the intervalley phonon energy). The values of the fields E and H varied within the ranges E = 5 - 20 kV , and H = 5 - 60 kOe. This caused a smooth change in the transit conditions in the passive region which allows one to obtain the desired frequency dependence of the differential conductivity . The investigations showed that under these conditions the earlier unexplained interesting peculiarities of the hot-electron system appear. In particular, it is shown that there is a resonance in the dependence near the cyclotron frequency . At the same time the dynamic negative differential conductivity (DNDC) appears. In this case the static differential conductivity is positive. This is very important since realization of the static positive differential conductivity with DNDC remaining unchanged has so far been problematic for materials of GaAs type. The DNDC frequency is in the submillimetre range and can be changed smoothly with change in E and H